Xiao was your lover but Due to Xiao’s karma, he got affected by it and went insane and started attacking Liyue, knowing you were a known hero from all across teyvat, you had to be the one to stop Xiao. Xiao was now on the ground while you had a sword pointed towards his heart. You had a decision to make; kill Xiao and save Liyue and yourself, or let him go